The constant-temperature liquid circulation apparatus which supplies the temperature-adjusted constant-temperature liquid to the load to cool or heat the load has been well known, in which an example thereof is disclosed in Patent literature 1. In general, this kind of constant-temperature liquid circulation apparatus has a configuration schematically illustrated in FIG. 3 and includes a constant-temperature liquid circuit 51 supplying a temperature-adjusted constant-temperature liquid to a load 50 in a circulating manner and a refrigeration circuit 52 adjusting a temperature of the constant-temperature liquid.
The constant-temperature liquid circuit 51 includes a tank 53 accommodating the constant-temperature liquid, a pump 54 supplying the constant-temperature liquid in the tank 53 to the load 50, and a cooling pipe 56 cooling the constant-temperature liquid, in which the temperature is risen by cooling of the load 50, by heat exchange with a refrigerant in a heat exchanger 55 to return the cooled constant-temperature liquid to the tank 53.
In addition, the refrigeration circuit 52 includes a compressor 57 compressing a gaseous refrigerant to change the refrigerant into a high-temperature and high-pressure gaseous refrigerant, an air-cooling condenser 58 cooling the high-temperature and high-pressure gaseous refrigerant sent from the compressor 57 to change the refrigerant into a high-pressure liquid refrigerant, a fan 59 forcing cooling air to flow into the condenser 58, an expansion valve 60 expanding the high-pressure liquid refrigerant sent from the condenser 58 to change the refrigerant into a low-temperature and low-pressure liquid refrigerant, and an evaporator 61 evaporating the low-temperature and low-pressure liquid refrigerant sent from the expansion valve 60 by heat exchange with the constant-temperature liquid in the heat exchanger 55 to change the refrigerant into a low-pressure gaseous refrigerant, thereby sending the low-pressure gaseous refrigerant to the compressor 57.
The inside of the refrigeration circuit 52 is divided into a high-pressure side portion in which the refrigerant pressure is high and a low-pressure side portion in which the refrigerant pressure is low. The high-pressure side portion is a portion extending from the compressor 57 to the expansion valve 60 via the condenser 58, and on the other hand, the low-pressure side portion is a portion extending from the expansion valve 60 to the compressor 57 via the evaporator 61.
Here, a refrigerant pressure at the high-pressure side portion depends on a condensation temperature which is a temperature when a gaseous refrigerant is liquefied inside the condenser 58. For example, the refrigerant pressure becomes higher when the condensation temperature is high, and the refrigerant pressure becomes lower when the condensation temperature is low.
In addition, when the condenser 58 is an air-cooling type, the refrigerant pressure at the high-pressure side portion depends on an ambient temperature (particularly, outside air temperature) of the constant-temperature liquid circulation apparatus, a ventilation rate of cooling air flowing into the condenser 58 by the fan 59, a flow rate of the refrigerant discharged from the compressor 57. That is, the condensation temperature rises and the refrigerant pressure also rises when the ambient temperature rises, and the condensation temperature falls and the refrigerant pressure is also lowered when the ambient temperature falls. In addition, when the rotation speed of the fan 59 increases and the ventilation rate of the cooling air increases, the condensation temperature falls and the refrigerant pressure is also lowered, and when the rotation speed of the fan 59 decreases and the ventilation rate of the cooling air decreases, the condensation temperature rises and the refrigerant pressure also rises. Further, when the flow rate of the refrigerant discharged from the compressor 57 is reduced, the condensation temperature falls and the refrigerant pressure is lowered, and the flow rate of the refrigerant discharged from the compressor 57 increases, the condensation temperature rises and the refrigerant pressure also rises.
When the refrigerant pressure at the high-pressure side portion becomes too high, a dangerous state is caused in an excess of a withstand pressure limit of piping or use parts. For this reason, the constant-temperature liquid circulation apparatus of the related art is configured to increase the rotation speed of the fan 59 and to increase the flow rate of the cooling air when the refrigerant pressure at the high-pressure side portion is increased. However, even when the rotation speed of the fan 59 is increased to the maximum rotation speed, the refrigerant pressure continues to rise due to, for example, the influence of the ambient temperature in some cases. In these cases, the damage of the piping or use parts is prevented by stopping the operation of the compressor 57.
However, in the case of stopping the operation of the compressor 57, since the refrigeration circuit does not function or the operation of the entire constant-temperature liquid circulation apparatus should be stopped, it is difficult to adjust the temperature of the constant-temperature liquid.